Systems, devices, and methods for eyebox expansion in wearable heads-up display

ABSTRACT

Systems, devices, and methods for eyebox expansion in wearable heads-up displays (WHUD) are described. A WHUD includes a support structure, a scanning laser projector (SLP), a split mirror, an optical splitter, and a holographic combiner. When the WHUD is worn on the head of a user the holographic combiner is positioned in a field of view of the user. The SLP scans light signals onto the split mirror which reflects the light signals onto the optical splitter. The optical splitter redirects the light signals towards the holographic combiner such that subsets of the light signals originate from spatially-separated virtual positions. The holographic combiner redirects the light to the eye resulting in spatially-separated exit pupils. The spatial separation of the exit pupils results in an expanded eyebox. The indirect path of light from SLP to optical splitter enables a smaller and therefore more aesthetically desirable design for the WHUD.

TECHNICAL FIELD

The present systems, devices, and methods generally relate to wearableheads-up displays and particularly relate to eyebox expansion inwearable heads-up displays.

BACKGROUND Description of the Related Art Laser Projectors

A projector is an optical device that projects or shines a pattern oflight onto another object (e.g., onto a surface of another object, suchas onto a projection screen) in order to display an image or video onthat other object. A projector necessarily includes a light source, anda laser projector is a projector for which the light source comprises atleast one laser. The at least one laser is temporally modulated toprovide a temporal pattern of laser light and usually at least onecontrollable mirror is used to spatially distribute the modulatedtemporal pattern of laser light over a two-dimensional area of anotherobject. The spatial distribution of the modulated temporal pattern oflaser light produces a series of images at or on the other object. Inconventional laser projectors, the at least one controllable mirror mayinclude: a single digital micromirror (e.g., a microelectromechanicalsystem (“MEMS”) based digital micromirror) that is controllablyrotatable or deformable in two dimensions, or two digital micromirrorsthat are each controllably rotatable or deformable about a respectivedimension, or a digital light processing (“DLP”) chip comprising anarray of digital micromirrors.

Wearable Heads-Up Displays

A head-mounted display is an electronic device that is worn on a user'shead and, when so worn, secures at least one electronic display within aviewable field of at least one of the user's eyes, regardless of theposition or orientation of the user's head. A wearable heads-up displayis a head-mounted display that enables the user to see displayed contentbut also does not prevent the user from being able to see their externalenvironment. The “display” component of a wearable heads-up display iseither transparent or at a periphery of the user's field of view so thatit does not completely block the user from being able to see theirexternal environment. Examples of wearable heads-up displays include:the Google Glass®, the Optinvent Ora®, the Epson Moverio®, and the SonyGlasstron®, just to name a few.

Eyebox

In near-eye optical devices such as rifle scopes and wearable heads-updisplays, the range of eye positions (relative to the device itself)over which specific content/imagery provided by the device is visible tothe user is generally referred to as the “eyebox.” An application inwhich content/imagery is only visible from a single or small range ofeye positions has a “small eyebox” and an application in whichcontent/imagery is visible from a wider range of eye positions has a“large eyebox.” The eyebox may be thought of as a volume in spacepositioned near the optical device. When the eye of the user (and moreparticularly, the pupil of the eye of the user) is positioned insidethis volume and facing the device, the user is able to see all of thecontent/imagery provided by the device. When the eye of the user ispositioned outside of this volume, the user is not able to see at leastsome of the content/imagery provided by the device.

The geometry (i.e., size and shape) of the eyebox is an importantproperty that can greatly affect the user experience for a wearableheads-up display. For example, if the wearable heads-up display has asmall eyebox that centers on the user's pupil when the user is gazingdirectly ahead, some or all content displayed by the wearable heads-updisplay may disappear for the user when the user gazes even slightlyoff-center, such as slightly to the left, slightly to the right,slightly up, or slightly down. Furthermore, if a wearable heads-updisplay that has a small eyebox is designed to align that eyebox on thepupil for some users, the eyebox will inevitably be misaligned relativeto the pupil of other users because not all users have the same facialstructure. Unless a wearable heads-up display is deliberately designedto provide a glanceable display (i.e., a display that is not alwaysvisible but rather is only visible when the user gazes in a certaindirection), it is generally advantageous for a wearable heads-up displayto have a large eyebox.

Demonstrated techniques for providing a wearable heads-up display with alarge eyebox generally necessitate adding more bulky optical componentsto the display. Technologies that enable a wearable heads-up display ofminimal bulk (relative to conventional eyeglass frames) to provide alarge eyebox are generally lacking in the art.

BRIEF SUMMARY

A wearable heads-up display may be summarized as including: a supportstructure that in use is worn on a head of a user; a holographiccombiner carried by the support structure and positioned in a field ofview of the user when the support structure is worn on the head of theuser; a scanning laser projector carried by the support structure, thescanning laser projector to output light signals; an optical splittercarried by the support structure, the optical splitter comprising atleast one optical element arranged to receive light signals generated bythe scanning laser projector and redirect each light signal towards theholographic combiner effectively from one of N spatially-separatedvirtual positions for the scanning laser projector, where N is aninteger greater than 1, the particular virtual position for the scanninglaser projector from which a light signal is redirected by the opticalsplitter determined by a point of incidence at which the light signal isreceived by the optical splitter; and a split mirror carried by thesupport structure, the split mirror comprising at least two non-coplanarreflective surfaces to receive light signals from the scanning laserprojector and redirect the light signals towards the optical splitter.

The support structure may have the shape and appearance of an eyeglassframe, and the wearable heads-up display may further include an eyeglasslens carried by the support structure, wherein the transparent combinerin carried by the eyeglass lens.

The holographic combiner may converge the light signals to at least twoexit pupils at or proximate the eye of the user.

The scanning laser projector may include: a red laser diode to outputred laser light, a green laser diode to output green laser light, a bluelaser diode to output blue laser light, a beam combiner to combine thered laser light, green laser light, and blue laser light into anaggregate beam, and at least one controllable mirror to scan theaggregate beam across the split mirror.

The split mirror may be a single unitary element with at least twonon-coplanar reflective surfaces. The split mirror may include a firstelement having at least one reflective surface and a second elementhaving at least one reflective surface. Each reflective surface of thesplit mirror redirects light to a distinct and non-overlapping region ofthe optical splitter. Each reflective surface of the split mirrorredirects a discrete set of light signals towards the optical splitter.

The optical splitter may have N non-coplanar input surfaces to receivelight signals from the split mirror, where N is an integer greater than1, and an output surface to direct light towards the holographiccombiner, the output surface positioned across a thickness of theoptical splitter from the input surfaces. Alternatively, the opticalsplitter may have an input surface to receive light signals from thesplit mirror, and N non-coplanar output surfaces to direct light towardsthe holographic combiner, where N is an integer greater than 1, theoutput surfaces positioned across a thickness of the optical splitterfrom the input surface.

The split mirror may be positioned to receive at least 90% of the lightsignals output by the scanning laser projector. The optical splitter maybe positioned to receive at least 90% of the light signals reflected bythe split mirror.

A method of operating a wearable heads-up display (WHUD) when the WHUDis worn on a head of a user, the WHUD including a scanning laserprojector having a scan range, a split mirror having at least twonon-coplanar reflective surfaces, an optical splitter, and a holographiccombiner, may be summarized as including: generating light signals bythe scanning laser projector; scanning the light signals towards thesplit mirror across the scan range by the scanning laser projector;directing the light signals towards the optical splitter by the splitmirror; directing the light signals towards the holographic combiner bythe optical splitter, wherein the optical path of a respective lightsignal from the optical splitter to the holographic combiner isdetermined by a respective point of incidence and angle of incidence ofthe respective light signal at the optical splitter; and directing thelight signals towards an eye of the user by the holographic combiner.

Directing the light signals towards an eye of the user by theholographic combiner may further include directing the light signals toat least two exit pupils at or proximate the eye of the user.

The scanning laser projector may include a red laser diode, a greenlaser diode, a blue laser diode, a beam combiner, and at least onecontrollable mirror, and generating light signals by the scanning laserprojector may further include: generating red laser light by the redlaser diode; generating green laser light by the green laser diode; andgenerating blue laser light by the blue laser diode; wherein the methodfurther includes: combining the red laser light, green laser light, andblue laser light into aggregate light signals; and wherein: scanning thelight signals towards the split mirror across the scan range by thescanning laser projector further includes scanning the light signalstowards the split mirror by the at least one controllable mirror.

Directing the light signals towards the optical splitter by the splitmirror may further include: directing the light signals towardsrespective distinct and non-overlapping regions of the optical splitterby each respective non-coplanar reflective surface of the split mirror.

Directing the light signals towards the optical splitter by the splitmirror may further includes: directing respective discrete sets of lightsignals towards the optical splitter by each respective non-coplanarreflective surface of the split mirror.

Scanning the light signals towards the split mirror across the scanrange by the scanning laser projector may further include: scanning atleast 90% of the light signals onto the split mirror by the scanninglaser projector.

The method of operating the wearable heads-up display may furtherinclude receiving at least 90% of the reflected light signals from thesplit mirror by the optical splitter.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

In the drawings, identical reference numbers identify similar elementsor acts. The sizes and relative positions of elements in the drawingsare not necessarily drawn to scale. For example, the shapes of variouselements and angles are not necessarily drawn to scale, and some ofthese elements are arbitrarily enlarged and positioned to improvedrawing legibility. Further, the particular shapes of the elements asdrawn are not necessarily intended to convey any information regardingthe actual shape of the particular elements, and have been solelyselected for ease of recognition in the drawings.

FIG. 1 is an isometric view of a wearable heads-up display in accordancewith the present systems, devices, and methods.

FIG. 2 is a schematic diagram of a wearable heads-up display inaccordance with the present systems, devices, and methods.

FIG. 3 is a schematic diagram of an optical splitter and two reflectivesurfaces of a split mirror of a wearable heads-up display in accordancewith the present systems, device and methods.

FIG. 4 is a flow diagram of a method of operating a wearable heads-updisplay with a scanning laser projector in accordance with presentsystems, devices, and methods.

DETAILED DESCRIPTION

In the following description, certain specific details are set forth inorder to provide a thorough understanding of various disclosedembodiments. However, one skilled in the relevant art will recognizethat embodiments may be practiced without one or more of these specificdetails, or with other methods, components, materials, etc. In otherinstances, well-known structures associated with portable electronicdevices and head-worn devices, have not been shown or described indetail to avoid unnecessarily obscuring descriptions of the embodiments.

Unless the context requires otherwise, throughout the specification andclaims which follow, the word “comprise” and variations thereof, suchas, “comprises” and “comprising” are to be construed in an open,inclusive sense, that is as “including, but not limited to.”

Reference throughout this specification to “one embodiment” or “anembodiment” means that a particular feature, structures, orcharacteristics may be combined in any suitable manner in one or moreembodiments.

As used in this specification and the appended claims, the singularforms “a,” “an,” and “the” include plural referents unless the contentclearly dictates otherwise. It should also be noted that the term “or”is generally employed in its broadest sense, that is as meaning “and/or”unless the content clearly dictates otherwise.

The headings and Abstract of the Disclosure provided herein are forconvenience only and do not interpret the scope or meaning of theembodiments.

The various embodiments described herein provide systems, devices, andmethods for splitter optics that, among other potential applications,have particular utility in eyebox expansion in scanning laser-basedwearable heads-up displays (“WHUDs”). Generally, a scanning laser-basedWHUD is a form of virtual retina display in which a scanning laserprojector (“SLP”) draws a raster scan onto the eye of the user. In theabsence of any further measure, the SLP projects light over a fixed areacalled the exit pupil of the display. In order for the user to seedisplayed content the exit pupil typically needs to align with, beencompassed by, or overlap with the entrance pupil of the user's eye.The full resolution and/or field of view of the display is visible tothe user when the exit pupil of the display is completely containedwithin the entrance pupil of the eye. For this reason, a scanninglaser-based WHUD typically employs a relatively small exit pupil that isequal to or smaller than the expected size of the entrance pupil of theuser's eye (e.g., less than or equal to about 4 mm in diameter).

The eyebox of a scanning laser-based WHUD is defined by the geometry ofthe exit pupil of the display at or proximate the eye of the user. Ascanning laser-based WHUD that employs a small exit pupil in order toachieve maximum display resolution and/or field of view typically hasthe drawback of having a relatively small eyebox. For example, the exitpupil may be aligned with the center of the user's eye so that the eye'spupil is located “within the eyebox” when the user is gazing directlyahead but the eye's pupil may quickly leave the eyebox if and when theuser glances anywhere off-center. A larger eyebox may be achieved byincreasing the size of the exit pupil but this typically comes at thecost of reducing the display resolution and/or field of view. Inaccordance with the present systems, devices, and methods, the eyebox ofa scanning laser-based WHUD may be expanded by optically replicating orrepeating a relatively small exit pupil and spatially distributingmultiple copies or instances of the exit pupil over a relatively largerarea of the user's eye, compared to the area of the single exit pupil onits own. In this way, at least one complete instance of the display exitpupil (either as a single instance in its entirety or as a combinationof respective portions of multiple instances) may be contained withinthe perimeter of the eye's pupil for each of a range of eye positionscorresponding to a range of gaze directions of the user. In other words,the present systems, devices, and methods describe eyebox expansion byexit pupil replication in scanning laser-based WHUDs.

Throughout this specification and the appended claims, the term“replication” and its variants are used (e.g., in the context of “exitpupil replication”) to generally refer to situations where multipleinstances of substantially the same exit pupil and/or display contentare produced. The term “exit pupil replication” is intended to generallyencompass approaches that produce concurrent (e.g., temporally parallel)instances of an exit pupil as well as approaches that produce sequential(e.g., temporally serial or “repeated”) instances of an exit pupil.Unless the specific context requires otherwise, references to “exitpupil replication” herein include exit pupil replication by exit pupilrepetition.

Throughout this specification and the appended claims, the term“holographic combiner” is used to generally refer to a holographicoptical element which allows environmental light to pass through to aneye of a user and redirects display light from a light source to the eyeof the user such that the environmental light and display light are“combined” and are both visible to the user. The holographic combinermay comprise at least one hologram, volume diffraction grating, surfacerelief diffraction grating, and/or reflection grating.

FIG. 1 is an isometric view of a wearable heads-up display (WHUD) 100 inaccordance with the present systems, devices, and methods. WHUD 100includes a support structure 160 that is worn on the head of a user, atleast one eyeglass lens 150, a scanning laser projector 110, a splitmirror 120, an optical splitter 130, and a holographic combiner 140carried by eyeglass lens 150. Holographic combiner 140 is positioned ina field of view of an eye of the user when the support structure is wornon the head of the user. Scanning laser projector 110 includes a redlaser diode 111, a green laser diode 112, a blue laser diode 113, a beamcombiner 114, and a controllable mirror 115. Split mirror 120 has tworeflective surfaces that are non-coplanar. In alternativeimplementations, split mirror 120 could have more than two reflectivesurfaces. Optical splitter 130 has two non-coplanar input surfaces andone output surface, the output surface is positioned across a thicknessof the optical splitter from the input surfaces. In alternativeimplementations, optical splitter 130 could have more than twonon-coplanar input surfaces and one output surface or could have oneinput surfaces and multiple non-coplanar output surfaces. WHUD 100operates as follows.

Red laser diode 111 generates red laser light, green laser diode 112generates green laser light, and blue laser diode 113 generates bluelaser light. Beam combiner 114 is comprised of reflective mirrors, beamsplitters, and/or dichroic mirrors and combines the red laser light,green laser light, and blue laser light into an aggregate beam. A personof skill in the art will appreciate that the aggregate beam may compriselight from only one of the laser diodes, any two of the laser diodes, orall three of the laser diodes in order to create a full color image. Theaggregate beam is scanned towards split mirror 120 by controllablemirror 115. Controllable mirror 115 may be a single mirror that isrotatable or deformable in two dimensions or may be two mirrors that areeach rotatable or deformable in a single dimension (e.g., orthogonaldimensions such as horizontal and vertical). Controllable mirror 115 mayraster scan an image onto the two reflective surfaces of split mirror120. Split mirror 120 reflects light signals created by the scanning ofthe aggregate beam towards optical splitter 130. In FIG. 1, opticalsplitter 130 has a first input surface and a second input surface and asingle output surface. Each of the two reflective surfaces of splitmirror 120 reflects a set of light signals towards a respective inputsurface of optical splitter 130. That is, a first distinct set of lightsignals is incident on the first input surface and a second distinct setof light signals is incident on the second input surface. Opticalsplitter 130 redirects the light signals towards holographic combiner140. The path of a respective light signal from optical splitter 130 toholographic combiner 140 is dependent on the point of incidence of therespective light signal on optical splitter 130. The input surfaces ofoptical splitter 130 are oriented and positioned to alter the path ofthe respective light signals incident thereon such that the two sets oflight signals appear to be originating from spatially-separated virtualpositions. The virtual positions are separated by more than the actualphysical positions of the points of incidence of the light signals onthe input surfaces. Holographic combiner 140 redirects the light signalsto the eye of the user. Each of the two sets of light signals representsa spatially-separated exit pupil at the eye of the user. These exitpupils may show the same image resulting in exit pupil replication atthe eye of the user. WHUD 100 may have N number of spatially-separatedexit pupils, wherein N is any integer greater than 1. That is, opticalsplitter 130 may redirect lights signals from N spatially-separatedvirtual positions. Optical splitter 130 may have N input surfaces toredirect the light signals.

Optical splitter 130 and WHUD 100 may be similar to the optical splitterand the wearable heads-up display previously described in U.S.Non-Provisional patent application Ser. No. 15/147,638 (hereafter “Ser.No. 15/147,638”) and US Patent Application Publication No. 2016-0377866A1/U.S. Non-Provisional patent application Ser. No. 15/046,254(hereafter “2016-0377866”). The wearable heads-up display of both Ser.No. 15/147,638 and 2016-0377866 has a housing for the optical splitter(Ser. No. 15/147,638 and 2016-0377866, both FIG. 1, element 150) thatjuts out from the surrounding support structure in order to create anoptimal distance between the scanning laser projector, specifically thescan mirror, and the optical splitter. This architecture is functionalbut for a more fashionable wearable heads-up display a smaller housingis desirable. The optical splitter and controllable mirror of Ser. No.15/147,638 and 2016-0377866 could be brought closer together to decreasethe size of the housing if the scan range of the controllable mirror wasincreased, but this would decrease the quality of the image created.With the addition of split mirror 120, the housing that holds opticalsplitter 130 can be decreased in size because the position ofcontrollable mirror 115 (equivalent to the scan mirror) is held by splitmirror 120. Split mirror 120 does not have a scan range and thereforecan be positioned closer to optical splitter 130 than the scan mirror ofSer. No. 15/147,638 and 2016-0377866 without decreasing image quality.The configuration of WHUD 100 may allow for all of the light scannedfrom controllable mirror 115 to be spread across both of split mirror120 and optical mirror 130 resulting in minimal losses in image quality(e.g., image resolution).

FIG. 2 is a schematic diagram of a wearable heads-up display 200 inaccordance with the present systems, devices, and methods. WHUD 200 maybe similar to WHUD 100 of FIG. 1 and includes a scanning laser projector210, a split mirror 220, an optical splitter 230, and a holographiccombiner 240 carried on an eyeglass lens 250. Scanning laser projector210 includes a red laser diode 211, a green laser diode 212, a bluelaser diode 213, a beam combiner 214, and a controllable mirror 215. Asupport structure of WHUD 200 (not shown) is worn on the head of a userand may have the shape and appearance of eyeglasses. WHUD 200 operatesas follows.

Red laser diode 211 generates red laser light, green laser diode 212generates green laser light, and blue laser diode 213 generates bluelaser light. Beam combiner 214 combines the red laser light, green laserlight, and blue laser light into an aggregate beam 270 (solid linearrows; only one arrow labelled to reduce clutter) and directs aggregatebeam 270 towards controllable mirror 215. Beam combiner 214 comprisesreflective mirrors, beam splitters, and/or dichroic mirrors.Controllable mirror 215 scans aggregate beam 270 onto split mirror 220(two solid arrows used to show scan range of aggregate beam fromcontrollable mirror 215 to split mirror 220). Controllable mirror 215may be a single mirror (e.g., a microelectromechanical system (“MEMS”)based digital micromirror) that is controllably rotatable or deformablein two dimensions, or two mirrors that are each controllably rotatableor deformable about a respective dimension. Split mirror 220 has tworeflective surfaces, 221 and 222, which both receive scanned aggregatebeam 220 from controllable mirror 215. Split mirror 220 may be a singleunitary element having two reflective surfaces (as shown), or may be twoseparate elements: a first element having a first reflective surface anda second element having a second reflective surface. The reflectivesurfaces of split mirror 220 are positioned to receive at least 90% andpreferably 100% of the light scanned from controllable mirror 215 whilemaximizing the area of the reflective surfaces upon which light inincident. That is, preferably split mirror 220 is sized and positionedsuch that the dimensions of the reflective surface of split mirror 220are the same as the dimensions of the scan area of controllable mirror215 when aggregate beam 270 is incident on split mirror 220. Splitmirror 220 reflects aggregate beam 270 towards optical splitter 230.Optical splitter 230 has two input surfaces 231 and 232, which are notcoplanar, and one output surface 233. Output surface 233 is positionedacross a thickness of optical splitter from the input surfaces. Inanother embodiment, optical splitter 230 may have more than twonon-coplanar input surfaces and each of reflective surface 221 andreflective surface 222 may direct light to more than one input surface.For example, optical splitter 230 may have four input surfaces andreflective surface 221 may direct light to first and second inputsurfaces while reflective surface 222 may direct light to third andfourth input surfaces. Aggregate beam 270 is reflected from split mirror220 as two sets of light signals 271 and 272. Light signals 271 (dashedline arrows; sets of two arrows represent the outer boundaries of thelight signals; only one arrow labelled to reduce clutter) are reflectedfrom reflective surface 221 to input surface 231. Light signals 272(dotted line arrows; set of two arrows represent outer boundaries of thelight signals; only one arrow labelled to reduce clutter) are reflectedfrom reflective surface 222 to input surface 232. Optical splitter 230is positioned to receive at least 90% and preferably 100% of lightreflected by split mirror 220 while maximizing the area of the inputsurfaces upon which light is incident. Optical splitter 230 directslight signals 271 and light signals 272 towards holographic combiner240. Light signals 271 and light signals 272 are redirected towardsholographic combiner 240 by optical splitter 230 from twospatially-separated virtual positions. That is, the path of a respectivelight signal (from light signals 271 or light signals 272) from opticalsplitter 230 to holographic combiner 240 is determined by the point ofincidence and the angle of incidence of the light signal on opticalsplitter 230. The point of incidence and angle of incidence of arespective light signal on optical splitter 230 is determined by thereflection of the respective light signal from split mirror 220. Lightsignals 271 and light signals 272 are redirected by the holographiccombiner towards an eye 280 of a user. Because light signals 271 andlight signals 272 are directed from two spatially-separated virtualpositions they are also incident at eye 280 at two spatially-separatedexit pupils. In this way the eyebox of the wearable heads-up display isincreased in size. Each of light signals 271 and light signals 272represent the same image, resulting in exit pupil replication at the eyeof the user. Environmental light 290 in the field of view of eye 280passes through eyeglass lens 260 and holographic combiner 240, allowingthe user to see both the display and their environment. In otherembodiments, WHUD 200 may include an eye tracking system whereinscanning laser projector 210 includes an infrared laser diode andinfrared laser light is scanned onto eye 280 and infrared lightreflected from eye 280 is captured and analyzed to determine a positionof any number of features (e.g. pupil, cornea, etc.) of eye 280.

FIG. 3 is a schematic diagram of an optical splitter 330 and tworeflective surfaces, 321 and 322, of a split mirror (not fully shown) ofa wearable heads-up display in accordance with the present systems,device and methods. The wearable heads-up display may be similar to WHUD100 and WHUD 200 and includes a support structure (not shown), ascanning laser projector (not fully shown), the split mirror (not fullyshown), optical splitter 330, and a holographic combiner carried on aneyeglass lens (not shown). The scanning laser projector may includelaser diodes to generate laser light, a beam combiner to combine laserlight into an aggregate beam (if there are multiple laser diodes), and acontrollable mirror 315. The split mirror is similar to split mirror 120of FIG. 1 and split mirror 220 of FIG. 2 and includes reflective surface321 and reflective surface 322. Optical splitter 330 is similar tooptical splitter 130 of FIG. 1 and optical splitter 230 of FIG. 2, andhas a single output surface, but has four input surfaces 331, 332, 333,and 334, instead of two Input surfaces 331, 332, 333, and 334 arenon-coplanar and are positioned across a thickness of optical splitter330 from the output surface. In operation of the wearable heads-updisplay, aggregate beam 370 generated by the laser diodes and incidenton controllable mirror 315 is scanned onto reflective surface 321 andreflective surface 322. Reflective surface 321 and reflective surface322 are not co-planar. Reflective surface 321 and reflective surface 322reflect discrete subsets of light signals produced by the scanning ofaggregate beam 370 (arrows 370 represents all of the light scanned fromcontrollable mirror 315 and incident on reflective surfaces 321 and 322)towards optical splitter 330. Reflective surface 321 reflects lightsignals 371 (single arrow 371 represents all of the light incident onand reflected by the top half of reflective surface 321) towards inputsurface 331 and reflects light signals 373 (single arrow 373 representsall of the light incident on and reflected by the bottom half ofreflective surface 321) towards input surface 333. Reflective surface322 reflects light signals 372 (single arrow 372 represents all of thelight incident on and reflected by the top half of reflective surface322) towards input surface 332 and reflects light signals 374 (singlearrow 374 represents all of the light incident on and reflected by thebottom half of reflective surface 322) towards input surface 334. Lightsignals 371, 372, 373, and 374 exit the output surface of opticalsplitter 330 and are directed towards the holographic combiner, andsubsequently towards an eye of the user. The path of a respective lightsignal from optical splitter 330 to the holographic combiner isdetermined by the points of incidence and angles of incidence of therespective light signal at optical splitter 330. The path from opticalsplitter 330 to the holographic combiner of light signals 371 isdetermined by the points of incidence and angles of incidence of thelight signals on input surface 331. The path from optical splitter 330to the holographic combiner of light signals 372 is determined by thepoints of incidence and angles of incidence of the light signals oninput surface 332. The path from optical splitter 330 to the holographiccombiner of light signals 373 is determined by the points of incidenceand angles of incidence of the light signals on input surface 333. Thepath from optical splitter 330 to the holographic combiner of lightsignals 374 is determined by the points of incidence and angles ofincidence of the light signals on input surface 334. Each of lightsignals 371, light signals 372, light signals 373, and light signals 374exit the output surface on a path towards the holographic combiner thatrepresents a spatially-separated virtual position. That is, lightsignals 371, light signals 372, light signals 373, and light signals 374appear to have originated from respectively different locations, theselocations being further apart than if the light was directed to theholographic combiner directly from the split mirror. The holographiccombiner redirects each set of light signals such that light signals371, light signals 372, light signals 373, and light signals 374 eachrepresent a spatially-separated exit pupil at the eye of the user. Thespatial separation of the four exit pupils creates a larger eyebox thancould be achieved if the exit pupils were not separated by opticalsplitter 330. Each of light signals 371, lights signals 372, lightsignals 373, and light signals 374 represent a copy of the same image,wherein the aggregate beam scans four “identical” tiled images onto thesplit mirror, two images onto reflective surface 321 and two images ontoreflective surface 322, resulting in exit pupil replication at the eyeof the user. The position and orientation of controllable mirror 315,reflective surface 321, and reflective surface 322 are such thatreflective surface 321 and reflective surface 322 receive at least 90%and preferably 100% of aggregate beam 370 scanned from controllablemirror while aggregate beam 370 is scanned onto at least 90% andpreferably 100% of the areas of reflective surface 321 and reflectivesurface 322. The position and orientation of reflective surface 321,reflective surface 322, and optical splitter 330 are such that the inputsurfaces 331, 332, 333, and 334 of optical splitter 330 receive at least90% and preferably 100% of the light reflected from reflective surface321 and reflective surface 322 while light signals 371, light signals372, light signals 373, and light signals 374 are incident on at least90% and preferably 100% of input surface 331, input surface 332, inputsurface 333, and input surface 334, respectively.

FIG. 4 is a flow diagram of a method of operating a wearable heads-updisplay with a scanning laser projector in accordance with presentsystems, devices, and methods. The wearable heads-up display of FIG. 4may be similar to WHUD 100 of FIG. 1, WHUD 200 of FIG. 2, and the WHUDdescribed in FIG. 3, and includes a scanning laser projector, a splitmirror having at least two non-coplanar reflective surfaces, an opticalsplitter, and a holographic combiner. The WHUD of FIG. 4 may comprise asupport structure having the shape and appearance of eyeglasses. TheWHUD positions a display in the field of view of an eye of a user whenworn on a head of the user. Method 400 includes acts 401, 402, 403, 404,and 405, though those of skill in the art will appreciate that inalternative embodiments certain acts may be omitted and/or additionalacts may be added. Those of skill in the art will also appreciate thatthe illustrated order of the acts is shown for exemplary purposes onlyand may change in alternative embodiments.

At 401, the scanning laser projector generates light signals. Theselight signals may be generated by at least one laser diode, wherein abeam combiner combines multiple beams into an aggregate beam if multiplelaser diodes are employed. The at least one laser diode may include ared laser diode to generate red laser light, a green laser diode togenerate green laser light, and a blue laser diode to generate bluelaser light. The WHUD may include a processor and a non-transitoryprocessor-readable storage medium wherein the processor executes dataand/or instructions from the non-transitory processor-readable storagemedium to generate the light signals.

At 402, the light signals are scanned across a scan range of thescanning laser projector towards the split mirror. The light signals maybe scanned by at least one controllable mirror. The at least onecontrollable scan mirror may be one mirror that is controllablydeformable or rotatable to scan in two dimensions or two scan mirrorsthat are each controllably deformable or rotatable in respectivedimensions, the respective dimensions different from one another. Atleast 90%, and preferably 100%, of the light signals scanned by thescanning laser projector may be incident on the split mirror.

At 403, the split mirror directs the light signals towards the opticalsplitter, wherein each respective light signal is directed towards theoptical splitter at a respective angle of incidence. The split mirrorhas at least two reflective surfaces, and each reflective surface mayreflect a discrete subset of the light signals towards the opticalsplitter. Each reflective surface may reflect light signals towards adistinct and non-overlapping region of the optical splitter. Thesedistinct, non-overlapping regions of the optical splitter may be atleast two non-coplanar input surfaces. The split mirror may comprise asingle element having two reflective surfaces that are not co-planar, ormay comprise two elements each with one reflective surface, wherein thetwo reflective surfaces are not co-planar. At least 90%, and preferably100%, of the light signals reflected by the split mirror may be incidenton the optical splitter.

At 404, the optical splitter directs the light signals towards theholographic combiner, wherein the path of a respective light signal isdetermined by the point of incidence and the angle of incidence of therespective light signal on the optical splitter. The optical splitterdirects the light signals towards the holographic combiner from Nspatially-separated virtual positions, where N is an integer greaterthan 1. The optical splitter may have N input surfaces upon which thelight signals are incident. These input surfaces may be angled withrespect to the split mirror and not co-planar with each other or mayapply different optical functions to the light signals incident thereonsuch that respective subsets of the light signals incident on respectiveinput surfaces of the optical splitter are directed towards theholographic combiner from different virtual positions (the virtualpositions being different than the position the light originated from atthe split mirror). The optical splitter may have a single input surfaceand the optical functions applied to the respective subsets of lightsignals by the optical splitter may be applied within the opticalsplitter or at multiple non-coplanar output surfaces and may depend onthe point of incidence and angle of incidence of a respective lightsignal on the single input surface of the optical splitter.

At 405, the holographic combiner directs the light signals towards aneye of a user. The respective subsets of light signals which weredirected towards the holographic combiner from different virtualpositions by the optical splitter are incident at the eye of the user asrespective exit pupils. Each respective subset of light signalsrepresents the same image, resulting in exit pupil replication at theeye of the user and a large eyebox.

A person of skill in the art will appreciate that the variousembodiments for expanding eyeboxes described herein may be applied innon-WHUD applications. For example, the present systems, devices, andmethods may be applied in non-wearable heads-up displays and/or in otherapplications that may or may not include a visible display.

A person of skill in the art will appreciate that the variousembodiments for expanding eyeboxes described herein may be applied inwearable heads-up displays which do not include holographic combiners.That is, any non-holographic transparent combiner which allowsenvironmental light to pass through to an eye of a user while alsoredirecting display light to the eye of the user may be used. An opticalelement which does not combine environmental light with display light atthe eye of the user but instead blocks environmental light from the eyeof the user may also be used.

A person of skill in the art will appreciate that the variousembodiments for expanding eyeboxes described herein may be applied innon-scanning laser projector wearable heads-up displays. That is, anon-laser light source for generating light signals may be employed,including but not limited to: a light-emitting diode (LED), an organiclight-emitting diode (OLED), a microLED, a microdisplay comprising LEDs,OLEDs, or microLEDs, and/or any other type of microdisplay. The wearableheads-up display may also not employ scanning of light signals to createa display, instead light signals may be projected directly onto a splitmirror without scanning, particularly in implementations which employ amicrodisplay.

A person of skill in the art will appreciate that the variousembodiments for expanding eyeboxes described herein may be applied towearable heads-up displays which employ alternative optical splitters tothe optical splitter described above. In other implementations, anoptical splitter may be any single optical element or group of opticalelements which cause light signals to diverge from an initial path suchthat the light signals arrive at an eye of a user from one of Nspatially-separated virtual positions, including but not limited to:waveguides, lightguides, optical fibers, dichroic mirrors, and/orprisms.

In some implementations, one or more optical fiber(s), waveguides, orlightguides may be used to guide light signals along some of the pathsillustrated herein.

The WHUDs described herein may include one or more sensor(s) (e.g.,microphone, camera, thermometer, compass, altimeter, and/or others) forcollecting data from the user's environment. For example, one or morecamera(s) may be used to provide feedback to the processor of the WHUDand influence where on the display(s) any given image should bedisplayed.

The WHUDs described herein may include one or more on-board powersources (e.g., one or more battery(ies)), a wireless transceiver forsending/receiving wireless communications, and/or a tethered connectorport for coupling to a computer and/or charging the one or more on-boardpower source(s).

The WHUDs described herein may receive and respond to commands from theuser in one or more of a variety of ways, including without limitation:voice commands through a microphone; touch commands through buttons,switches, or a touch sensitive surface; and/or gesture-based commandsthrough gesture detection systems as described in, for example, U.S.Non-Provisional patent application Ser. No. 14/155,087, U.S.Non-Provisional patent application Ser. No. 14/155,107, PCT PatentApplication PCT/US2014/057029, and/or U.S. Provisional PatentApplication Ser. No. 62/236,060, all of which are incorporated byreference herein in their entirety.

In this specification, the term “processor” is used. Generally,“processor” refers to hardware circuitry, in particular any ofmicroprocessors, microcontrollers, application specific integratedcircuits (ASICs), digital signal processors (DSPs), programmable gatearrays (PGAs), and/or programmable logic controllers (PLCs), or anyother integrated or non-integrated circuit that perform logicoperations.

Throughout this specification and the appended claims, infinitive verbforms are often used. Examples include, without limitation: “to detect,”“to provide,” “to transmit,” “to communicate,” “to process,” “to route,”and the like. Unless the specific context requires otherwise, suchinfinitive verb forms are used in an open, inclusive sense, that is as“to, at least, detect,” to, at least, provide,” “to, at least,transmit,” and so on.

The above description of illustrated embodiments, including what isdescribed in the Abstract, is not intended to be exhaustive or to limitthe embodiments to the precise forms disclosed. Although specificembodiments of and examples are described herein for illustrativepurposes, various equivalent modifications can be made without departingfrom the spirit and scope of the disclosure, as will be recognized bythose skilled in the relevant art. The teachings provided herein of thevarious embodiments can be applied to other portable and/or wearableelectronic devices, not necessarily the exemplary wearable electronicdevices generally described above.

For instance, the foregoing detailed description has set forth variousembodiments of the devices and/or processes via the use of blockdiagrams, schematics, and examples. Insofar as such block diagrams,schematics, and examples contain one or more functions and/oroperations, it will be understood by those skilled in the art that eachfunction and/or operation within such block diagrams, flowcharts, orexamples can be implemented, individually and/or collectively, by a widerange of hardware, software, firmware, or virtually any combinationthereof. In one embodiment, the present subject matter may beimplemented via Application Specific Integrated Circuits (ASICs).However, those skilled in the art will recognize that the embodimentsdisclosed herein, in whole or in part, can be equivalently implementedin standard integrated circuits, as one or more computer programsexecuted by one or more computers (e.g., as one or more programs runningon one or more computer systems), as one or more programs executed by onone or more controllers (e.g., microcontrollers) as one or more programsexecuted by one or more processors (e.g., microprocessors, centralprocessing units, graphical processing units), as firmware, or asvirtually any combination thereof, and that designing the circuitryand/or writing the code for the software and or firmware would be wellwithin the skill of one of ordinary skill in the art in light of theteachings of this disclosure.

When logic is implemented as software and stored in memory, logic orinformation can be stored on any processor-readable medium for use by orin connection with any processor-related system or method. In thecontext of this disclosure, a memory is a processor-readable medium thatis an electronic, magnetic, optical, or other physical device or meansthat contains or stores a computer and/or processor program. Logicand/or the information can be embodied in any processor-readable mediumfor use by or in connection with an instruction execution system,apparatus, or device, such as a computer-based system,processor-containing system, or other system that can fetch theinstructions from the instruction execution system, apparatus, or deviceand execute the instructions associated with logic and/or information.

In the context of this specification, a “non-transitoryprocessor-readable medium” can be any element that can store the programassociated with logic and/or information for use by or in connectionwith the instruction execution system, apparatus, and/or device. Theprocessor-readable medium can be, for example, but is not limited to, anelectronic, magnetic, optical, electromagnetic, infrared, orsemiconductor system, apparatus or device. More specific examples (anon-exhaustive list) of the computer readable medium would include thefollowing: a portable computer diskette (magnetic, compact flash card,secure digital, or the like), a random access memory (RAM), a read-onlymemory (ROM), an erasable programmable read-only memory (EPROM, EEPROM,or Flash memory), a portable compact disc read-only memory (CDROM),digital tape, and other non-transitory media.

The various embodiments described above can be combined to providefurther embodiments. To the extent that they are not inconsistent withthe specific teachings and definitions herein, all of the U.S. patents,U.S. patent application publications, U.S. patent applications, foreignpatents, foreign patent applications and non-patent publicationsreferred to in this specification and/or listed in the Application DataSheet which are owned by Thalmic Labs Inc., including but not limitedto: US Patent Application Publication No. 2016-0377866 A1 US, US PatentApplication Publication No. 2016-0377865, US Patent ApplicationPublication No. US 2014-0198034 A1, US Patent Application PublicationNo. US 2016-0238845 A1, US Patent Application Publication No. US2014-0198035 A1, Non-Provisional patent application Ser. No. 15/046,234,U.S. Non-Provisional patent application Ser. No. 15/046,254, U.S.Non-Provisional patent application Ser. No. 15/145,576, U.S.Non-Provisional patent application Ser. No. 15/145,609, U.S.Non-Provisional patent application Ser. No. 15/147,638, U.S.Non-Provisional patent application Ser. No. 15/145,583, U.S.Non-Provisional patent application Ser. No. 15/256,148, U.S.Non-Provisional patent application Ser. No. 15/167,458, U.S.Non-Provisional patent application Ser. No. 15/167,472, U.S.Non-Provisional patent application Ser. No. 15/167,484, U.S.Non-Provisional patent application Ser. No. 15/381,883, U.S.Non-Provisional patent application Ser. No. 15/331,204, U.S.Non-Provisional patent application Ser. No. 15/282,535, U.S. ProvisionalPatent Application Ser. No. 62/271,135 U.S. Provisional PatentApplication Ser. No. 62/268,892, U.S. Provisional Patent ApplicationSer. No. 62/322,128, U.S. Provisional Patent Application Ser. No.62/420,368, U.S. Provisional Patent Application Ser. No. 62/420,371,U.S. Provisional Patent Application Ser. No. 62/420,380, U.S.Provisional Patent Application Ser. No. 62/438,725, U.S. ProvisionalPatent Application Ser. No. 62/374,181, U.S. Provisional PatentApplication Ser. No. 62/482,062, U.S. Provisional Patent ApplicationSer. No. 62/557,551, U.S. Provisional Patent Application Ser. No.62/557,554, U.S. Provisional Patent Application Ser. No. 62/565,677,U.S. Provisional Patent Application Ser. No. 62/573,978, and U.S.Provisional Patent Application Ser. No. 62/501,587 are incorporatedherein by reference, in their entirety. Aspects of the embodiments canbe modified, if necessary, to employ systems, circuits and concepts ofthe various patents, applications and publications to provide yetfurther embodiments.

These and other changes can be made to the embodiments in light of theabove-detailed description. In general, in the following claims, theterms used should not be construed to limit the claims to the specificembodiments disclosed in the specification and the claims, but should beconstrued to include all possible embodiments along with the full scopeof equivalents to which such claims are entitled. Accordingly, theclaims are not limited by the disclosure.

1. A method of operating a wearable heads-up display (WHUD) when theWHUD is worn on a head of a user, the WHUD including a scanning laserprojector having a scan range, a split mirror having at least twonon-coplanar reflective surfaces, an optical splitter, and a holographiccombiner, the method comprising: generating light signals by thescanning laser projector; scanning the light signals towards the splitmirror across the scan range by the scanning laser projector; directingthe light signals towards the optical splitter by the split mirror;directing the light signals towards the holographic combiner by theoptical splitter, wherein the optical path of a respective light signalfrom the optical splitter to the holographic combiner is determined by arespective point of incidence and angle of incidence of the respectivelight signal at the optical splitter; and directing the light signalstowards an eye of the user by the holographic combiner.
 2. The method ofclaim 1 wherein directing the light signals towards an eye of the userby the holographic combiner further includes directing the light signalsto at least two exit pupils at or proximate the eye of the user.
 3. Themethod claim 1 wherein the scanning laser projector includes a red laserdiode, a green laser diode, a blue laser diode, a beam combiner, and atleast one controllable mirror, and wherein generating light signals bythe scanning laser projector further includes: generating red laserlight by the red laser diode; generating green laser light by the greenlaser diode; and generating blue laser light by the blue laser diode;wherein the method further includes: combining the red laser light,green laser light, and blue laser light into aggregate light signals;and wherein: scanning the light signals towards the split mirror acrossthe scan range by the scanning laser projector further includes scanningthe light signals towards the split mirror by the at least onecontrollable mirror.
 4. The method of claim 1 wherein directing thelight signals towards the optical splitter by the split mirror furtherincludes: directing the light signals towards respective distinct andnon-overlapping regions of the optical splitter by each respectivenon-coplanar reflective surface of the split mirror.
 5. The method ofclaim 1 wherein directing the light signals towards the optical splitterby the split mirror further includes: directing respective discrete setsof light signals towards the optical splitter by each respectivenon-coplanar reflective surface of the split mirror.
 6. The method ofclaim 1 wherein scanning the light signals towards the split mirroracross the scan range by the scanning laser projector further includes:scanning at least 90% of the light signals onto the split mirror by thescanning laser projector.
 7. The method of claim 1 further including:receiving at least 90% of the reflected light signals from the splitmirror by the optical splitter.